A205007 a(n) = (1/n)*A205006(n), where A205006(n) = s(k)-s(j), with (s(k),s(j)) the least pair of distinct triangular numbers for which n divides their difference.

2, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1

Offset

1,1

Comments

For a guide to related sequences, see A204892.

Links

Antti Karttunen, Table of n, a(n) for n = 1..23515

Mathematica

(See the program at A205002.)

Prog

(PARI) A205007(n) = for(k=2, oo, my(sk=binomial(k+1, 2)); for(j=1, k-1, if(!((sk-binomial(j+1, 2))%n), return((sk-binomial(j+1, 2))/n)))); \\ Antti Karttunen, Sep 27 2018

Crossrefs

Cf. A000217, A205002, A205006, A204892.

Cf. A318894 (gives the positions terms larger than one).

Sequence in context: A030346 A030336 A321650 * A078470 A230799 A279496

Adjacent sequences: A205004 A205005 A205006 * A205008 A205009 A205010

Keyword

nonn

Author

Clark Kimberling, Jan 21 2012

Extensions

More terms from Antti Karttunen, Sep 27 2018

Status

approved